1. Field of the Invention
This invention relates to Caralluma extract, more particularly, to Caralluma extract products and to processes for making the same.
2. Description of the Related Art
The Caralluma group of plants belongs to the Asclepiadaceae family and comprises a number of species that are distributed throughout the world. Some of these species include but are not limited to: c. indica, c. fimbriata, c. attenuata, c. tuberculata, c. edulis, c. adscendens, c. stalagmifera, c. umbellata, c. penicillata, c. russeliana, c. retrospiciens, c. arabica and c. lasiantha. Some of the species are distributed throughout various parts of India.
Caralluma plants are small, erect and fleshy. They have 4 grooved stems that are almost round in shape. They are generally devoid of leaves and form small flowers in a variety of dark colors. Their pods are erect, linear and about 2.5 cms in length and feel velvety to the touch. The thorns of Caralluma are soft. The species of Caralluma found in India are edible and form part of the traditional medicine system of the country.
The medicinal properties of Caralluma includes carminative, febrifugal, anthelmintic, anti-rheumatic, anti-diabetic and anti-hyperglycaemic, anti-pyretic, anti-inflammatory, anti-nociceptive, and anti-oxidant effects. The Caralluma extracts have been also found to be appetite-suppressants as well as CNS stimulants.
The medicinal properties of Caralluma have been attributed to the glycosides contained therein. A glycoside is a condensation product obtained from a sugar and non-sugar compound and may have further components such as ring structures that are substituted or non-substituted. The glycosides contained in Caralluma belong to the pregnane group of glycosides. Some of the pregnane group of glycosides found in Caralluma plants include, but are not limited to:                i. caratuberside A,        ii. caratuberside B,        iii. bouceroside I,        iv. bouceroside II,        v. bouceroside III,        vi. bouceroside IV,        vii. bouceroside V,        viii. bouceroside VI,        ix. bouceroside VII,        x. bouceroside VIII,        xi. bouceroside IX, and        xii. bouceroside X.        
Another important property of Caralluma glycosides is their surprising synergy. This synergy was first observed by the present inventors. The synergy is exhibited by pairs of Caralluma glycosides and by higher order combinations, although the synergy contributed by the higher order combinations is not of much significance, in view of the fact that the content of glycosides other than the above-mentioned two, namely, caratuberside and bouceroside in Caralluma is extremely small. The caratuberside-bouceroside synergy is therefore, only one of the synergies found in Caralluma glycosides. The synergies found in Caralluma glycosides include the synergy arising out of isomer-isomer interactions in the two glycosides. The synergy is particularly strong with respect to the following three physiological effects of the glycosides: a reduction of body weight and treatment of obesity in subjects; a reduction of blood glucose in subjects and a reduction or elimination of arthritic and other joint pains. The uses of Caralluma for these physiological effects and the method of treatment thereof using Caralluma was first studied and investigated by the present inventors. The present inventors are also the first to study the related subject of the increase of muscle mass in subjects by use of Caralluma and the method of treatment for the same using Caralluma.
An interesting fact first observed by the present inventors is that the maximum caratuberside-bouceroside synergy is found when the caratuberside-bouceroside ratio is substantially equal to the CB ratio found in c. indica. Three other species, namely, fimbriata, attenuata and tuberculata have substantially the same ratio value and substantially the same glycoside content as c. indica. These four species are referred to hereinafter as Group I Caralluma species. Four more species, namely, stalagmifera, umbellata, lasiantha and edulis also have substantially the same CB ratio but somewhat lesser total content of glycosides than the Group I species. The latter four species are referred to hereinafter as Group II species and the caratuberside-bouceroside ratio is referred to as the CB ratio, or the CBR for short.
The prior art provides a process for extraction of Caralluma wherein the aerial parts of Caralluma plants are extracted by means of 10% aq. ethanol. The prior art process has a number of drawbacks and furthermore results in only a crude extract product that is not standardized, that is non-reproducible and that is not representative of the original plant material from which it is extracted. These drawbacks of the prior art product and process are described further hereinbelow.
In the first reference (M. N. M. Zakaria, M. W. Islam, R. Radhakrishnan, H. B. Chan, M. Kamil, A. N. Gifri, K. Chan, A. Al-Attas, J. of Ethnophamacology, 76 (2001), 155-158), c. arabica, a Caralluma species found in West Asia, was extracted using 10% aq. ethanol. The aerial parts of the plant were dried in the shade, powdered and then extracted with 10% aq. ethanol. The solvent was removed from the extract by evaporation under vacuum at 40° C. using a rotary evaporator. The dried extract was re-suspended in distilled water and the slurry used for a pharmacological investigation to establish the anti-nociceptive and anti-inflammatory properties of c. arabica with respect to mice and rats.
In the second reference (M. Kamil, A. F. Jayaraj, F. Ahmed, C. Gunasekhar, S. Samuel, K. Chan, M. Habibullah, J. Pham. Pharmacol. 1999, 5: (Supplement), 225), powdered c. arabica plant material was extracted using 10% aq. ethanol in a soxhlet extractor for eight hours. The flavone glycosides, luteolin-4′-O-nehesperidoside and kaempferol-7-O-nehesperidoside were isolated from the extract and the concentrations thereof in c. Arabica determined.
In the third reference (R. Radhakrishnan, M. N. M. Zakaria, M. W. Islam, X. M. Liu, K. Chan, M. Habibulah, J. Pham. Pharmacol., 1999, 5 (Supplement), 116.) and the fourth reference (M. N. M. Zakaria, M. W. Islam, R. Radhakrishnan, H. B. Chan, A. Ismail, K. Chan, M. Habibulah, J. Pharm. Pharmacol. 1999, 5 (Supplement), 117), the aerial parts of c. arabica are stated to have been extracted by means of 10% ethanol. No further details of the adopted process are disclosed.
The first drawback among the drawbacks of the prior art process is that decomposition of the Caralluma glycosides occurs during processing. This fact was not recognized by the prior art and was first observed by the present inventors. When a Caralluma extract (solution) is concentrated by evaporation of solvent therein, charring and overheating of material occurs at higher concentrations. The overheating/charring causes the decomposition despite the provision of considerable agitation.
The charring/overheating is primarily caused by the high viscosities of the Caralluma extracts of high concentrations. The high viscosities are caused by the presence of the resinous matter of Caralluma plants that get extracted out in the extract along with the glycosides. The present inventors observe that under certain conditions of extraction considerable quantities of the resins are extracted out along with the glycosides.
The decomposition was observed first by the present inventors both in the concentration step and in the extraction step. Where the extraction temperature is held at levels higher than 75° C., thermal decomposition of the glycosides occurs. Such high temperatures enhance the viscosity of the extract and increase the risk of decomposition in the concentration step.
In a soxhlet type apparatus, because of the column effect, the Caralluma plant matter would come into contact with solvent vapors that have a much greater ethanol content than 10% that is used to charge the apparatus. The extraction temperature would also remain generally above 75° C. Under these conditions, the present inventors have observed that considerable decomposition occurs and furthermore large quantities of the resinous matter in Caralluma plant matter get extracted out into the extract.
The process conditions are not fully disclosed in the third and fourth references but it is fair to assume that the extracts are evaporated to dryness to obtain the product in a solid form suitable for pharmacological studies. Thus, the decomposition must certainly occur in the method adopted by the third and fourth references.
The second drawback of the prior art process is that the non-glycoside components in Caralluma are extracted. The non-glycoside components are tannins, pectins and the resinous matter and others. The present inventors have found that at low ethanol concentrations considerable quantities of tannins and pectins are extracted out with the glycosides while at high concentrations the resins go preferentially into solution. These inventors observe that, when 10% aq. ethanol is used, an extract contains considerable percentage of the tannins and pectins. So, in the process conditions adopted in the first, third and fourth references, the Caralluma extract obtained would have considerable impurities in the form of tannins and pectins that have a deleterious effect on the shelf life of the glycoside product. In the second reference, ethanol concentrations of over 80% are likely to be encountered by the Caralluma plant matter in the soxhlet apparatus. The present inventors have found that the extract under these conditions would contain high amounts of the Caralluma resins.
The third drawback of prior art is that the Caralluma extract product obtained by the prior art process is non-standard in so far as the composition thereof would vary from one extraction to another. It is unrepresentative in so far as it would not reflect fully either the various constituents of Caralluma glycosides or their relative proportions that are found in the original plant matter. Further, as the composition would vary from extract to extract the Caralluma extract product of the prior art process cannot be considered to be reproducible.
Apart from the pharmacological studies of a few of the medicinal aspects of Caralluma, the prior art does not provide for any concrete medical applications of Caralluma. The present inventors have pioneered such applications. The applications would require Caralluma constituents in various forms such as tablets, injectables and others which would have to be made from a suitable intermediate that contains the principles of Caralluma. Such an intermediate that contains the principles of Caralluma and that could be the starting point is neither known or defined in the prior art.
In summary, the drawbacks of the prior art process include, but are not limited to:                i. non-standardized, non-representative and non-reproducible product;        ii. process conditions conducive to the decomposition of the glycosides;        iii. the extraction of undesirable non-glycoside components of Caralluma into the extracts, such as the tannins, pectins and resins that would affect the purity and storage properties of the product and that have side effects on the subjects treated with Caralluma glycoside products;        iv. no provision for removal of the undesirable non-glycoside components from the extracts in the process of prior art; and        v. process parameters not optimized from the point of view of process economics or from the point of view of obtaining the desirable Caralluma intermediate product(s).        